An automotive meter having an illuminated pointer is proposed in U.S. Pat. No. 6,655,209. The pointer is structured so that it is observed as if its illuminated length is altered according to on/off conditions of a key switch. A cross-sectional view of the meter is shown in FIG. 10 and a circuit diagram of its light emitting circuit for the pointer is shown in FIG. 11.
The pointer 100 has a printed circuit board (PCB) 101 in its longitudinal direction, and light emitting diodes (LEDs) 102a through 102j are arranged on a surface of the PCB 101 at regular intervals. Resistors 103a through 103j and zener diodes 104a through 104j are arranged on the other surface of the PCB 101 at locations corresponding to relative LEDs 102a–102j. A terminal 106 is extended from the PCB 101 on a side adjacent to a boss. A voltage is applied to the LEDs 102a–102j, the resistors 103a–103j, and the zener diodes 104a–104j via the terminal 106.
In the light emitting circuit, the resistors 103a–103j and the zener diodes 104a–104j are connected in series with the respective LEDs 102a–102j. Each series connection is connected in parallel with other series connections. A saturation voltage of each zener diode 104a–104j are set so that the diodes 104a–104j are lined according to levels of the saturation voltages that vary from low to high as they go away from the boss side.
The pointer 100 is illuminated by applying a voltage, a level of which becomes higher as elapsed time becomes longer as shown in FIG. 12, to end terminals 107a, 107b of the light emitting circuit via the terminal 106. The LED 102a is illuminated at time t1 at which the zener diode 104a is saturated and the LED 102b is illuminated at time t2 at which the zener diode 104b is saturated. The LEDs 102a–102j are illuminated in sequence from the boss side to the other as time passes. With this configuration, the pointer 100 is observed as if it stretches from its base portion to its tip.
In this meter, a number of LEDs 102a–102j, the resistors 103a–103j, and the zener diodes 104a–104j are fixed to the pointer 100 throughout its length. Thus, the pointer 100 becomes heavy in weight, especially at its tip, and an inertia moment of the pointer 100 increases. Moreover, the barycentric point moves toward the tip and the unbalanced weight increases. Therefore, high-performance movement for rotating the pointer 100 is required, and an application of this meter to an actual instrument is difficult.